An oligomeric integral membrane glycoprotein complex that appears to mediate a transmembrane linkage between the cytoskeleton and extracellular matrix has been identified, purified, and partially characterized. This complex functions in cell-matrix adhesion as a receptor for fibronectin and laminin. It has a second binding site for talin, a cytoskeletal associated molecule thought to link actin filaments to the membrane. The domains that participate in ECM adhesion and talin binding will be identified and their topography determined. Analogous experiments will be done on live cells. The goals is to provide convincing evidence that the CSAT antigen serves as an ECM- cytoskeletal link. The oligomeric subunits will be sequenced by recombinant DNA techniques. The structure of small, biologically active domains will be determined by 2-D NMR and overall conformational features determined by electron microscopy with domain specific monoclonal antibody probes. The organization, neighbors, and role of the antigen in the different kinds of adhesions of muscle, including the myotendonouse and neuromuscular junctions, will be characterized. Alterations of antigen structure and function after transformation and during mitosis will be investigated. Finally, the locus and kinetics of biogenesis, membrane insertion, and organization into supra-molecular assemblies will be determined.